Neurophysiological Evaluation of Neural Transmission in Brachial Plexus Motor Fibers with the Use of Magnetic versus Electrical Stimuli.

The anatomical complexity of brachial plexus injury requires specialized in-depth diagnostics. The clinical examination should include clinical neurophysiology tests, especially with reference to the proximal part, with innovative devices used as sources of precise functional diagnostics. However, the principles and clinical usefulness of this technique are not fully described. The aim of this study was to reinvestigate the clinical usefulness of motor evoked potential (MEP) induced by a magnetic field applied over the vertebrae and at Erb's point to assess the neural transmission of brachial plexus motor fibers. Seventy-five volunteer subjects were randomly chosen to participate in the research. The clinical studies included an evaluation of the upper extremity sensory perception in dermatomes C5-C8 based on von Frey's tactile monofilament method, and proximal and distal muscle strength by Lovett's scale. Finally, 42 healthy people met the inclusion criteria. Magnetic and electrical stimuli were applied to assess the motor function of the peripheral nerves of the upper extremity and magnetic stimulus was applied to study the neural transmission from the C5-C8 spinal roots. The parameters of compound muscle action potential (CMAP) recorded during electroneurography and MEP induced by magnetic stimulation were analyzed. Because the conduction parameters for the groups of women and men were comparable, the final statistical analysis covered 84 tests. The parameters of the potentials generated by electrical stimulus were comparable to those of the potentials induced by magnetic impulse at Erb's point. The amplitude of the CMAP was significantly higher following electrical stimulation than that of the MEP following magnetic stimulation for all the examined nerves, in the range of 3-7%. The differences in the potential latency values evaluated in CMAP and MEP did not exceed 5%. The results show a significantly higher amplitude of potentials after stimulation of the cervical roots compared to potentials evoked at Erb's point (C5, C6 level). At the C8 level, the amplitude was lower than the potentials evoked at Erb's point, varying in the range of 9-16%. We conclude that magnetic field stimulation enables the recording of the supramaximal potential, similar to that evoked by an electric impulse, which is a novel result. Both types of excitation can be used interchangeably during an examination, which is essential for clinical application. Magnetic stimulation was painless in comparison with electrical stimulation according to the results of a pain visual analog scale (3 vs. 5.5 on average). MEP studies with advanced sensor technology allow evaluation of the proximal part of the peripheral motor pathway (between the cervical root level and Erb's point, and via trunks of the brachial plexus to the target muscles) following the application of stimulus over the vertebrae.

Results of a long-term uniform system of neurorehabilitation in patients with incomplete thoracic spinal cord injury.

INTRODUCTION AND OBJECTIVE: The results of kinesiotherapy treatment in patients after incomplete spinal cord injury (iSCI) are inconclusive, mostly due to different, subjective evaluation methods. The study aims to evaluate the range of functional regeneration in long-term 13 months follow-up using comparative neurophysiological tests after uniform kinesiotherapy in patients with thoracic iSCI. MATERIAL AND METHODS: Comparative tests were performed of sensory perception in dermatomes Th1-S1, electromyography (at rest-rEMG and during maximal contraction-mcEMG) in the muscles of the trunk and lower extremities, electroneurography (ENG) of the motor fibres of the lower extremities, and motor-evoked potential induced transcranially (MEP) before and after treatment in 25 iSCI patients. All subjects were treated with the same kinesiotherapeutic procedures. RESULTS: A moderate increase was found in amplitudes in rEMG and mcEMG recordings fromthe rectus abdominis and rectus femoris muscles, MEPs amplitudes, and amplitudes after peroneal nerve stimulations in ENG studies. There was no improvement in sensory perception. CONCLUSIONS: Following the proposed kinesiotherapy algorithm, patients after thoracic iSCI presented a moderate more motor than sensory functions improvement. Applied neurorehabilitation evoked normalization of muscle tension, moderate improvement of rectus abdominis and rectus femoris muscles motor units activity, and motor central and peripheral neural impulses transmission. The comparative neurophysiological assessment provide a more precise and objective insight into the functional status of afferent and efferent systems than the classical clinical approach in iSCI patients.

The Long-Term Effect of Treatment Using the Transcranial Magnetic Stimulation rTMS in Patients after Incomplete Cervical or Thoracic Spinal Cord Injury.

Repetitive transcranial magnetic stimulation (rTMS) may support motor function recovery in patients with incomplete spinal cord injury (iSCI). Its effectiveness mainly depends on the applied algorithm. This clinical and neurophysiological study aimed to assess the effectiveness of high-frequency rTMS in iSCI patients at the C2-Th12 levels. rTMS sessions (lasting 3-5 per month, from 2 to 11 months, 5 months on average) were applied to 26 iSCI subjects. The motor cortex was bilaterally stimulated with a frequency at 20-25 Hz and a stimulus strength that was 70-80% of the resting motor threshold (15.4-45.5% maximal output) during one therapeutic session. Surface electromyography (sEMG) recordings at rest and during maximal contractions and motor evoked potential (MEP) recordings were performed from the abductor pollicis brevis (APB) and the tibialis anterior (TA) muscles. The same neurophysiological studies were also performed in patients treated with kinesiotherapy only (K group, n = 25) and compared with patients treated with both kinesiotherapy and rTMS (K + rTMS). A decrease in sEMG amplitudes recorded at rest from the APB muscles (p = 0.001) and an increase in sEMG amplitudes during the maximal contraction of the APB (p = 0.001) and TA (p = 0.009) muscles were found in the K + rTMS group. A comparison of data from MEP studies recorded from both APB and TA muscles showed significant changes in the mean amplitudes but not in latencies, suggesting a slight improvement in the transmission of spinal efferent pathways from the motor cortex to the lower spinal centers. The application of rTMS at 20-25 Hz reduced spasticity in the upper extremity muscles, improved the recruitment of motor units in the upper and lower extremity muscles, and slightly improved the transmission of efferent neural impulses within the spinal pathways in patients with C2-Th12 iSCI. Neurophysiological recordings produced significantly better parameters in the K + rTMS group of patients after therapy. These results may support the hypothesis about the importance of rTMS therapy and possible involvement of the residual efferent pathways including propriospinal neurons in the recovery of the motor control of iSCI patients.

Treatment of patients with cervical and upper thoracic incomplete spinal cord injury using repetitive transcranial magnetic stimulation.

PURPOSE: To evaluate the short- and long-term effectiveness of repetitive transcranial magnetic stimulation with parameters based on results of comparative neurophysiological studies in patients with incomplete spinal cord injury. Results may help to understand mechanisms responsible for regeneration of the incomplete spinal cord after injury. METHODS: Repetitive transcranial magnetic stimulation sessions (three to five sessions per month for not less than 5 months) to 15 patients with C4-Th2 incomplete spinal cord injury were applied with individually designed parameters. One session consisted of bilateral stimulation of the primary motor cortex (for 10 min each with 800 stimuli in 2-s lasting trains and the inter-train intervals of 28 s) with frequency at 20-22 Hz and stimulus strength that was 70%-80% of the resting motor threshold (0.84-0.96 T). Recordings of surface electromyography at rest and during the attempt of maximal muscle contractions and motor evoked potentials were performed from abductor pollicis brevis and tibialis anterior muscles bilaterally. Amplitude parameters of surface electromyography and motor evoked potentials were used as outcomes. All neurophysiological tests were comparatively applied before and after treatment. RESULTS: Decrease in surface electromyography amplitudes recorded at rest from abductor pollicis brevis (p = 0.009), increase in surface electromyography amplitudes during maximal contraction of abductor pollicis brevis (p = 0.03) and increase in motor evoked potential parameters recorded from abductor pollicis brevis (p = 0.04) were found. CONCLUSION: Proposed repetitive transcranial magnetic stimulation algorithm reduced the increased muscle tension in upper extremity muscles, improved the function of upper extremity muscle motor units and slightly improved the transmission of efferent neural impulses within spinal pathways. Besides functional recovery in descending spinal pathways, repetitive transcranial magnetic stimulation may also inhibit inevitable pathological changes in nerves.

Relations between the results of complex clinical and neurophysiological examinations in patients with temporomandibular disorders symptoms.

OBJECTIVE: Reinvestigation of clinical importance of surface electromyography recordings (sEMG) from the masticatory, neck and shoulder girdle muscles in patients with various clinically detected temporomandibular disorders (TMDs). METHODS: Fifty women with myalgia diagnosis of Axis I DC/TMD and the same number of healthy female volunteers were studied clinically and neurophysiologically by means of sEMG. RESULTS: Unilateral more than bilateral complex symptoms of TMDs were related to the non-neurogenic masticatory rather than neck and shoulder girdle muscles dysfunctions at rest. A strong negative correlation between masticatory muscles activity at rest and during maximal contraction was found (rs = -0.778), mainly in the masseter muscle. CONCLUSION: sEMG is a suitable tool for prosthodontists because it provides objective results on the stomatognathic system muscles function. Pain and other temporomandibular symptoms detected mostly unilaterally significantly increase muscle tension of the masticatory muscles and diminish muscle motor units recruitment during maximal contraction. Effects may spread to the neck and shoulder girdle muscles.